Auto-cross-linked gellan gum

Abstract

The present invention is drawn to inner esters of gellan, wherein the carboxy groups are esterified with hydroxy groups from either the same or different molecules of gellan. The present invention is further drawn to methods of using the present inner esters of gellan in the fields of cosmetics, pharmaceuticals and in sanitary and surgical articles. The present invention is further drawn to products made from inner esters of gellan and to be used in the indicated fields.

What is claimed is:  
     
       1. Polymers of gellan wherein said gellan is 1-15% auto-cross-linked by lactone bonds between carboxy and hydroxy groups of the same molecule or by ester bonds between carboxy groups and hydroxy groups of different molecules of the polysaccharide itself, and wherein remaining carboxy groups may be free or toally or partially esterified with mono or polyvalent alcohols, and pharmaceutically acceptable salts of any free carboxy groups with inorganic or organic bases. 
     
     
       2. Polymers of gellan according to claim  1 , wherein only a part of the carboxy groups are involved in the auto-cross-linking process. 
     
     
       3. Polymers of partially auto-cross-linked gellan according to claim  1 , wherein the remaining carboxy groups are totally or partially esterified with aliphatic, araliphatic, cycloaliphatic or heterocyclic alcohols. 
     
     
       4. Pharmaceutical preparations containing as active ingredient a polymer according to claim  1  together with an excipient. 
     
     
       5. Medicaments containing: 
       a) a pharmacologically active substance or an association of pharmacologically active substances;  
       b) a carrying vehicle constituted by an auto-cross-linked polymer of gellan according to claim  1 .  
     
     
       6. Medicaments according to claim  5 , wherein component a) is a substance for oral, topical or local use. 
     
     
       7. Medicaments according to claim  5 , wherein component b) is an auto-cross-linked polymer of gellan gum, which is water-insoluble but swellable in water. 
     
     
       8. Medicaments according to claim  5  wherein component a) is an anesthetic, analgesic or anti-inflammatory agent, a vasoconstrictor, an antibiotic/antibacterial, an antiviral or an antifungal agent. 
     
     
       9. Medicaments according to claim  5  wherein component a) is a protein-derived agent. 
     
     
       10. Sanitary and surgical articles containing an auto-cross-linked gellan polymer according to claim  1 . 
     
     
       11. Sanitary and surgical articles according to claim  10  in the form of threads, gauzes and films. 
     
     
       12. Sanitary and surgical articles according to claim  10  in the form of non-woven tissues. 
     
     
       13. Sanitary and surgical articles according to claim  10  in the form of microspheres or microgranules. 
     
     
       14. Sanitary and surgical articles according to claim  10  constituted by sponges. 
     
     
       15. Cosmetic articles containing an auto-cross-linked gellan polymer according to claim  1 . 
     
     
       16. Alimentary articles containing an auto-cross-linked gellan polymer according to claim  1 . 
     
     
       17. Alimentary articles according to claim  16  in the form of membranes for the preservation of food. 
     
     
       18. A procedure for the preparation of threads or films of auto-cross-linked gellan polymers having 1-15% auto-cross-linking, wherein said polymers are dissolved in a first organic solvent, the solution is made into sheet or thread form, and the first solvent is eliminated. 
     
     
       19. The procedure according to claim  18  wherein the elimination of the first organic solvent is performed by treatment with a second suitable organic or aqueous solvent which is soluble in the first solvent, and in which the polymers are not soluble, and said second solvent is removed from the polymers. 
     
     
       20. A procedure according to claim  19 , wherein dimethylsulfoxide is used as the first solvent. 
     
     
       21. A procedure according to claim  19 , wherein hexafluoroisopropanol is used as the first solvent, and said solvent is eliminated with a current of suitably heated inert gas.